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81.
82.
83.
Kilo M Taylor MA Argirusis C Borchardt G Weber S Scherrer H Jackson RA 《The Journal of chemical physics》2004,121(11):5482-5487
The diffusion of all stable lanthanides was measured both in calcia stabilized zirconia (CSZ) and in yttria stabilized zirconia (YSZ) in the temperature range between 1,286 and 1,600 degrees C. The lanthanide diffusion coefficients obtained increase with increasing ionic radius. The experimental activation enthalpy of diffusion is near 6 eV for CSZ and between 4 and 5 eV for YSZ and is not strongly affected by the type of lanthanide. The results were correlated with defect energy calculations of the lanthanide diffusion enthalpy using the Mott-Littleton approach. An association enthalpy of cation vacancies with oxygen vacancies of about 1 eV (96 kJ/mol) was deduced in the case of CSZ, while there is no association in the case of YSZ. Furthermore, the change in diffusion coefficients can be correlated to the interaction parameter for the interaction between the lanthanide oxide with zirconia: The higher the interaction parameter, the higher the lanthanide diffusion coefficient. 相似文献
84.
Colson S Konczykowski M Gaifullin MB Matsuda Y Gierłowski P Li M Kes PH Van Der Beek CJ 《Physical review letters》2003,90(13):137002
Vortex thermal fluctuations in heavily underdoped Bi(2)Sr(2)CaCu(2)O(8+delta) (T(c)=69.4 K) are studied using Josephson plasma resonance. From the zero-field data, we obtain the c-axis penetration depth lambda(L,c)(0)=230+/-10 micrometer and the anisotropy ratio gamma(T). The low plasma frequency allows us to study phase correlations over the whole vortex solid state and to extract a wandering length r(w) of vortex pancakes. The temperature dependence of r(w) as well as its increase with dc magnetic field is explained by the renormalization of the vortex line tension by the fluctuations, suggesting that this softening is responsible for the dissociation of the vortices at the first order transition. 相似文献
85.
Vincent Besse Gabriel Foyer Rémi Auvergne Sylvain Caillol Bernard Boutevin 《Journal of polymer science. Part A, Polymer chemistry》2013,51(15):3284-3296
This article describes the synthesis of new cyclic compounds able to react with amines to get nonisocyanate polyurethanes (NIPUs). The contribution of the most studied five‐membered cyclic carbonate was compared to five‐membered cyclic dithiocarbonate analogous and to a six‐membered cyclic carbonate. Difunctional reactive species were obtained by a simple substitution reaction or an efficient thiol–ene coupling reaction. The products, obtained with high yields, were characterized by 1H NMR, 13C NMR, and Fourier tansform infrared spectroscopy analysis. The dicyclocarbonates were then used to synthesize NIPUs by step growth polymerization with several diamines. These materials exhibited glass transition temperatures from 19 to ?29 °C, molar mass from 1800 to 20,400 g mol?1, and a 20% mass loss temperature (Td = 20%) between 249 and 296 °C. Such materials are interesting candidates for coating applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3284–3296 相似文献
86.
Raoul Mens Sabine Bertho Sylvain Chambon Jan D'Haen Laurence Lutsen Jean Manca Jan Gelan Dirk Vanderzande Peter Adriaensens 《Journal of polymer science. Part A, Polymer chemistry》2011,49(7):1699-1707
The optimization and control of the nanomorphology of thin films used as active layer in bulk heterojunction (BHJ) plastic solar cells is of key importance for a better understanding of the photovoltaic mechanisms and for increasing the device performances. Hereto, solid‐state NMR relaxation experiments have been evaluated to describe the film morphology of one of the “work‐horse” systems poly(2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylene‐vinylene)/[6, 6]‐phenyl‐C61butyric acid methyl ester (MDMO‐PPV/PCBM) in a quantitative way. Attention is focused on the influence of the processing solvent (toluene vs. chlorobenzene), the blend composition, and the casting technique, that is, spin coating versus doctor blading. It is demonstrated that independently of the solvent and casting technique, part of the PCBM becomes phase separated from the mixed phase. Whereas casting from toluene results in the development of well‐defined PCBM crystallites, casting from chlorobenzene leads to the formation of PCBM‐rich domains that contain substructures of weakly organized PCBM nanoclusters. The amount and physico‐chemical state of the phase separated PCBM is quantified by solid‐state NMR relaxation times experiments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
87.
Eric Lamballais Véronique Fortuné Sylvain Laizet 《Journal of computational physics》2011,230(9):3270-3275
In this short note, we show how to use a highly accurate finite-difference scheme to compute second derivatives in the Navier–Stokes equations while ensuring targeted numerical dissipation. This approach, essentially non conservative, is shown to be close to an upwind method and is straightforward to implement with a negligible computational extra cost. The benefit offered by the resulting discrete operator is illustrated for the direct computation of sound in aeroacoustics and in the more general context of large-eddy simulation through connections with hyperviscosity and spectral vanishing viscosity. 相似文献
88.
Otfried Cheong Xavier Goaoc Andreas Holmsen Sylvain Petitjean 《Discrete and Computational Geometry》2008,39(1-3):194-212
We prove Helly-type theorems for line transversals to disjoint unit balls in ℝ
d
. In particular, we show that a family of n≥2d disjoint unit balls in ℝ
d
has a line transversal if, for some ordering ≺ of the balls, any subfamily of 2d balls admits a line transversal consistent with ≺. We also prove that a family of n≥4d−1 disjoint unit balls in ℝ
d
admits a line transversal if any subfamily of size 4d−1 admits a transversal.
Andreas Holmsen was supported by the Research Council of Norway, prosjektnummer 166618/V30. Otfried Cheong and Xavier Goaoc
acknowledge support from the French-Korean Science and Technology Amicable Relationships program (STAR). 相似文献
89.
An efficient synthesis of 9,10-disubstituted phenanthrenes is described in this Letter. These novel useful building blocks were obtained in a one-pot reaction including Suzuki-Miyaura cross-coupling followed by a Dieckmann-Thorpe ring closure under microwave irradiation. The selection of the appropriate reagents and the optimal reaction conditions to isolate the intermediate biphenyl compound or the final substituted phenanthrenes in high yields will be discussed in this Letter. 相似文献
90.
We report here several synthesis routes and their respective drawbacks/advantages for the preparation of pure LiFePO4. We demonstrate the possibility of using LiFePO4 for electrochemical applications, with respect that an effective carbon coating was realized onto the smallest particles. Actually, to bypass the weak ionic conductivity of lithium iron phosphate, the thinnest would be the particles; the highest would be the performance under severe electrochemical conditions. 相似文献